I differ--it serves the purpose of letting the child see you will defend him--even if he is wrong. The others are right--he did not tell on the boy with the knife and 'show responsibility'. My bad! CYA is today's game and has also created a dog eat dog world. Too bad it just didn't end where it began because it seemed innocent enough to me. I do question a 9 year old with a knife anywhere except at a Boy Scout meeting.
Of course you are right! My parents didn't teach me that one. They actually taught me to follow the rules at school.